.TH GAMMA 3M
.SH NAME
gamma
.SH DESCRIPTION
function gamma.f

source
  Bevington, page 126.

purpose
  calculate gamma function for integers and 1/2-integers

usage
  result = gamma (x)

description of parameters
  x      - integer or half-integer

subroutines or function subprograms required
  factor (n)
    calculates n factorial for integers
